1. Field of Invention
The present invention relates in general to housings for enclosing computer systems and in particular to vented doors with acoustic attenuation for use with such housings. More particularly, the present invention relates to a computer system which includes a vented door having a pivotable vented base and an outer door that is pivotable relative to the base.
2. Background Art
Computer systems are using larger amounts of energy, and are generating more heat. Increased heat generation is driven by factors such as increases in processor performance and clock speed, and increases in the number of devices per integrated circuit. Electronic components, such as microprocessors and integrated circuits, must operate within certain specific temperature ranges to perform efficiently. Excessive heat degrades electronic component performance, reliability, life expectancy, and can even cause failure. Air moving devices (AMDs), such as fans and blowers, are widely used for controlling excessive heat. AMDs are often used in combination with heat sinks thermally connected to electronic components to be cooled. Typically, heat sinks are formed with fins to increase the surface area of the heat sink and thereby enhance heat dissipation as air moved by an AMD passes over the heat sink.
In many large server applications, the processors of a computer system along with their associated electronics (e.g., memory, disk drives, power supplies, etc.) are packaged in removable drawer configurations stacked within a rack or frame. In other cases, the processors of a computer system along with their associated electronics may be in fixed locations within the rack or frame. Typically, the components are cooled by air moving in parallel air flow paths, usually front-to-back, impelled by one or more AMDs.
With the advent of the increased heat generated by computer systems, increased ventilation is required to move cooling air through the computer system. A failure to provide adequate ventilation through a computer system may increase the probability of computer failure due to overheating and may result in damage to the electronic components. Due to the great expense of these electronic components and the concomitant loss of processing time associated with such failures, it is desirable that adequate ventilation be maintained for computer systems. Increased air flow rates are needed to provide adequate ventilation. However, the acoustic noise associated with the increased air flow rates required to provide adequate ventilation, as well as acoustic noise generated by the various components within the computer system, represents a problem that must be overcome. There are limits on the acoustic output of computer systems (e.g., servers and storage products) set by vendors, governments, standards setting bodies, and the like.
In order to reduce acoustic noise, it is known to utilize an acoustic noise reduction lining in vented covers of computer systems. An example of such an arrangement is found in U.S. Pat. No. 5,526,228, issued Jun. 11, 1996 to Dickson et al., entitled “COMPUTER SYSTEM UNIT WITH ACOUSTIC DAMPENING COOLING FAN SHROUD PANEL”, which is assigned to the assignee of the present application. As shown in FIG. 1, a cooling fan shroud panel 16 includes an acoustic noise reduction lining comprising a side acoustic foam panel 28 and a top acoustic foam panel 30. The acoustic dampening cooling fan shroud panel 16 is mounted to an intermediate rear panel 32 of a computer system unit 10. Two cooling fans 34, 36 are mounted within fan mounting apertures 35, 37 of the intermediate rear panel 32. The cooling fans 34, 36 draw air through computer system unit 10 from an intake ventilation grill (not shown) of a front panel 12 in the direction indicated by the arrows designated with reference numeral 44. Mounted within computer system unit 10 are a power supply 38 and an electronic component package 40, which are cooled by the air drawn through computer system unit 10. Air is directed out an exiting ventilation aperture 22 of cooling fan shroud panel 16 in the direction indicated by the arrow designated with reference numeral 42. The exiting ventilation aperture 22 is displaced from the mounting position of the cooling fans 34, 36 such that acoustic noise resultant from the cooling fan operation is diminished. Even though acoustic dampening cooling fan shroud panel 16 is effective in diminishing acoustic noise, it exhibits a number of disadvantages. First, the relatively substantial depth of acoustic dampening cooling fan shroud panel 16 significantly increases the footprint of computer system unit 10. Second, the small area of exiting ventilation aperture 22 relative to intermediate rear panel 32 reduces the cooling efficiency.
FIG. 2 shows another example of the utilization of acoustic noise reduction lining in vented covers found in the IBM eServer zSeries 900 server. As shown in FIG. 2 (Top View), an inlet cover 210 includes an acoustic noise reduction lining comprising two outer acoustic foam panels 212 and central acoustic foam block 214. Inlet ventilation apertures 216 are defined between outer acoustic foam panels 212 and central acoustic foam block 214. Inlet cover 210 also includes intake extensions 213 and 215 that respectively project from one of the two outer acoustic foam panels 212 and central acoustic foam block 214. In addition, inlet cover 210 includes four curved vanes 217. Intake extensions 213, 215 and curved vanes 217 are configured and positioned to suitably direct and distribute the incoming air through inlet ventilation apertures 216 and toward the various heat generating components housed within a computer system frame or rack 200. Similarly, an exhaust cover 220 includes an acoustic noise reduction lining comprising two outer acoustic foam panels 222 and central acoustic foam block 224. Exhaust ventilation apertures 226 are defined between outer acoustic foam panels 222 and central acoustic foam block 224.
The inlet cover 210 and the exhaust cover 220 are mounted to computer system frame or rack 200 using hinges (not shown) so that removable drawers (not shown) stacked within computer system frame 200 may be accessed when inlet cover 210 and/or exhaust cover 220 is/are swung open via the hinges. AMDs (not shown) draw air through computer system frame 200 from inlet ventilation apertures 216 and exhaust the air through exhaust ventilation apertures 226. The air moves in the direction indicated by arrows designated by reference numeral 230. The removable drawers, which contain processors and their associated electronics, are cooled by the air drawn through computer system frame 200, as are electronic components fixed within computer system frame 200. Acoustic noise resultant from the AMD operation is effectively diminished by inlet cover 210 and exhaust cover 220 which have three main attributes: a large amount of acoustic absorbing material; an air/noise path that curves or angles to force sound to impact the acoustic lining; and minimum sharp bends in the air path to minimize airflow resistance.
Even though inlet cover 210 and exhaust cover 220 are effective in diminishing acoustic noise, they exhibit a number of disadvantages. First, the relatively substantial depth of inlet cover 210 and exhaust cover 220 significantly increase the footprint of computer system frame 200. For example, to accommodate a sufficient amount of acoustic foam and air inlet openings of sufficient size, the depth of inlet cover 210 (denoted as dimension “D” in FIG. 2) often exceeds 12 inches.
Second, the weight of inlet cover 210 and exhaust cover 220 can be excessive. For example, the weight of inlet cover 210 often approaches or exceeds the maximum weight one person is permitted to lift (e.g., 39.7 pounds). This situation is disadvantageous because it requires two customer engineers (CEs) to be sent on service calls.
Third, inlet cover 210 and exhaust cover 220 are dimensionally confined to an area within a physical envelope necessary to allow adjacent covers to hinge open against each other. The inlet cover 210 and exhaust cover 220 are typically chamfered 45° on each side as shown in FIG. 2 to allow adjacent cover doors to hinge open 90° against each other. Accordingly, the dimensions of inlet cover 210 and exhaust cover 220 are each limited to an area within a physical envelope (denoted in FIG. 2 as two dashed lines labeled as 240 with respect to inlet cover 210) that does not interfere with swinging one cover open 90° against an adjacent cover.
FIG. 3 shows an inlet cover 210 swung open 90° via one or more hinges (not shown) against an adjacent inlet cover 210, which is closed against its computer system frame 200. As mentioned above, each inlet cover may be swung open 90° to access components within its computer system frame, such a removable drawers.
It should therefore be apparent that a need exists for a computer system enclosure which can both adequately ventilate a computer system housed therein and reduce the amount of acoustic noise, while addressing the disadvantages of the prior art.